Side inlet rotary valve

ABSTRACT

A side inlet rotary valve for delivery of particulate material into a pneumatic conveyor system characterized by a vane-type rotor mounted for rotation about a horizontal axis in a generally cylindrical casing; the casing includes a downwardly opening outlet port connected to the pressurized system, a side inlet for introducing the material into the rotor chambers, and a pressure relief port above said side inlet for relief of pressure carried by the rotor chambers into the inlet region.

United States Patent Inventor Claude J. Miller Muncy, Pa. Appl. No.791,434 Filed Jan. 15, 1969 Patented Apr. 13, 1971 Assignee Sprout,Waldron & Company, Inc.

Muncy, Pa.

SIDE INLET ROTARY VALVE 4 Claims, 3 Drawing Figs.

US. Cl 302/49, 222/365 Int. Cl 865g 53/40 Field of Search 302/49;198/62; 222/194, 368

[56] References Cited UNITED STATES PATENTS 2,886,216 5/1959 Oholm302/49 3,224,813 12/1965 Jezo 302/49 3,311,420 3/1967 Halstead....302/49 3,399,931 9/1968 Vogt 302/49 Primary Examiner-Andres H. NielsenAtt0rneyHowson and Howson llHl HHIII SIDE INLET ROTARY VALVE The presentinvention relates generally to rotary valves for the metered feeding ofparticulate materials and relates more specifically to a side inletrotary valve adapted for the delivery of materials into a pneumaticconveyor system.

Rotary valves are presently in widespread use for the metered deliveryof granular free-flowing materials such as pellets, wood chips, and thelike. A typical application of such a valve is in the feeding ofmaterials from a storage hopper into a conveying system for transfer ofthe materials at a predetermined rate into processing equipment. Rotaryvalves are characterized in general by a cylindrical casing within whichis rotatably mounted in a vane-type rotor. The rotor and easing define aseries of compartments which, upon rotation of the rotor, acceptmaterial flowing under gravity force through a top inlet port anddischarge the material through a port in the bottom of the casing. Therate of material delivery is dependent essentially on the speed ofrotation of the valve rotor, the size of the inlet opening, and the flowcharacteristics of the material being transferred.

The top inlet-type rotary valve cannot be satisfactorily used with themore fragile granular materials because of the tendency of the materialsto shear between the edges of the vanes and the wall of the casing. Toovercome this problem, rotary valves have been constructed with thematerial inlet in the side of the casing opening into the upwardlymoving rotor vanes so that the material will settle down into the rotorcompartments by the time the compartments are sealed by the cylindricalcasing wall, normally just beyond the top dead center vane position.

The side inlet valve works well when delivering granular materials ontoa mechanical conveyor. However, when a pneumatic conveying system isutilized, the higher pressure at the valve discharge port charges thereturning rotor compartments with high-pressure air. The pressurizedcompartments upon opening into communication with the inlet port disruptthe inflow of materials and, under some circumstances, cause materialinflow into the valve to become completely stopped.

In the present invention, the casing of the side inlet rotary valve isprovided with a pressure relief port which is located above the materialinlet port and provides an exhaust passage for the high-pressure airwhich is carried from the bottom outlet port by the empty returningrotor compartments. By providing such a pressure relief, the materialinput into the casing continues smoothly and without interruption overthe normal range of operating speeds of the valve and relatively highpneumatic conveying pressures may be employed below the valve withoutaffecting valve operation.

It is accordingly a primary object of the present invention to provide aside inlet rotary valve for use with pneumatic conveying systems whichwill provide a smooth uninterrupted material flow at relatively highoutlet port pressures.

Additional objects of the invention will be more readily apparent fromthe following detailed description of an embodiment thereof when takentogether with the accompanying drawings, in which:

FIG. 1 is a plan view of a side inlet rotary valve in accordance withthe present invention;

FIG. 2 is a sectional view taken along line 22 of FIG. I and partlybroken away to show details of the rotor shaft seal; and

FIG. 3 is an enlarged vertical sectional view through a side inletrotary valve of the type shown in FIGS. 1 and 2 schematically showingthe manner in which the valve is connected with a pneumatic conveyingsystem and showing the passage of particulate material therethrough.

Referring to the drawings, the side inlet rotary valve generallydesignated embodying the present invention includes a valve casing '12having a vane-type rotor 14 rotatably mounted about a horizontal axistherein. The casing 12 includes a central cylindrical portion 16 havingend flanges 18 against which are secured the casing ends 20 and bearinghousings 22 within which are located the outboard rotor shaft bearings.

The rotor 14 includes a shaft 24 from which a plurality of vanes 26extend radially, the outer vane edges 28 being in closely fittingrelation with the inner surface 30 of the casing portion 16. The vanes26 extend axially between the rotor shrouds 32 which with the vanes andthe casing inner wall 30 form the rotor compartments 34.

As shown in FIG. 2, the shaft portions 36 outboard of the shrouds 32pass through the casing ends 20 wherein are mounted seal rings 38 heldin position by packing gland elements 40. The shaft ends 42 are joumaledin bearings (not shown) in the bearing housings 22 located outboard ofthe rotor to keep the bearings free of foreign matter and to minimizebearing wear and rotor misalignment.

As shown in FIG. I, the rotor is driven in rotation by a gear motor 44which is mounted on plate 46 secured to mounting brackets 48 integralwith the casing ends. A sprocket 50 on the gear motor output shaft 52 isconnected with a larger sprocket 54 on the extending end of the rotorshaft 24 by a suitable drive chain 56 shown schematically in FIG. 1.

As shown in FIG. 3, the cylindrical profile of the casing portion 16 isinterrupted in the upper casing region by the material side inletgenerally designated 60 which includes a material trough 62 inclined atapproximately 45 to the horizontal and which intersects the casing alongits horizontal centerline at 64. The casing includes a material inletport at 66 above the centerline 64 through which material may pass intothe rotor compartments 34 which are sequentially presented thereto uponcounterclockwise rotation of the rotor. A gate 68 which is inclined atapproximately 30 to the vertical limits the quantity of material whichmay flow into the rotor compartments, the quantity also being determinedas indicated above by the speed of rotation of the rotor and the angleof repose characteristic of the flowing material. The width X of theinlet trough 62 as shown in FIG. 2 is narrower than the axial width Y ofthe rotor compartments. The trough 62 in a typical installation isconnected by conduit 70 to a material storage hopper (not shown)positioned above the valve to permit a gravity feed of the material intothe valve.

Diametrically opposed from the inlet 66 is an outlet port 72 in thelower region of the casing through which the material may drop bygravity from the rotor compartments during rotation of the rotor. Aflanged casing extension 74 depending downwardly from the port 72 is, ina typical installation, connected by the material conduit 76 to apneumatic conveying system 78, a portion of which is schematicallyindicated as including a centrifugal blower 80 and a material conveyingduct 82 through which the material is driven by the pressure produced bythe blower. While air is normally employed as the conveying medium,other gases such as nitrogen may also be used.

To prevent the disruption of material flow through the inlet 66 by therelease of high-pressure air thereinto from the up wardly moving emptyrotor compartments, pressure relief means are provided in the form of apressure relief port 84 in the casing located above the inlet 66. Thecylindrical casing wall 30 is discontinued in the region 86 between theinlet 66 and the relief port 84 to permit the discharge of high-pressureair upwardly past the inlet. The air may pass into the region 86 throughthe entering particulate material or around the material. In addition,since the inlet passage as illustrated in FIG. 2 is preferably of awidth X substantially smaller than the axial width Y of the rotorcompartments, ample room is also provided at each side of the materialflow to permit the upward escape of the pressurized air from thecompartments as they successively open into the inlet region.

If the material handled is of a type which in handling generates asubstantial amount of dust, the relief port 84 may be connected asillustrated in FIG. 3 by a conduit 88 leading to a cyclone-typeseparator 90. Alternatively, the relief port 84 may be covered by afilter thereby permitting the pressurized air to be released into theatmosphere while retaining the dust within the valve.

The operation of the valve is to a large extent obvious from theforegoing description. With a head of granular freeflowing materialdisposed above the inlet trough 62, and with the blower 80 directing aflow of air or other suitable conveying gas into the conveying duct 82,the gear motor 44 is operated at a speed selected to give the desiredthroughput of material. With the rotor rotating counterclockwise asviewed in FIG. 3, as each rotor compartment 34 is presented to the inlet66, the high-pressure air in the compartment is released into the region86 and exhausted out of the relief port 84 into conduit 88 and theseparator 90. At the same time, the granular material 92 flows into theempty compartment in an amount limited by the angle of repose 94characteristic of the material, the speed of rotation of the rotor, andthe dimensions of the inlet opening 66. As the rotor vanes approach avertical attitude, the material introduced therebetween settles towardthe shaft 24 causing the material level 96 of each compartment to bespaced below the vane edges 28, thereby preventing the crushing orshearing of the granular material between the vane edges and the casingshoulder 98 which is angularly spaced beyond the vertical casingcenterline. As each compartment communicates with the outlet port 72,the material therein drops freely into the casing extension 74, conduit76 and thence into the duct 82 wherein it is entrained in an airstreamfor propulsion into a processing area. The communication of thecompartments with the outlet port charges the compartments withhighpressure air which is carried around to the inlet region and isexhausted through the relief port 84.

From the foregoing it can be understood that the flow of materialsthrough the inlet 66 will not be affected by the release of pressurizedgas from the rotor compartments. By provision of the relief port 84above the inlet 66 and a suitable relief of the casing wall in theregion 86 coupled with the width of the inlet X being smaller than thewidth of the rotor compartments Y permits a smooth passage of thepressurized air around each side of the inflowing materials to theregion 86 and out the relief port 84. Consequently, material input intothe rotor is smooth and uninterrupted over the operating speed range ofthe valve. With the present structure, pressures in the output region ashigh as to 12 p.s.i. are permissible whereas with conventional valvesthis pressure is normally limited to about 4 psi.

Manifestly, changes in details of construction can be effected by thoseskilled in the art without departing from the spirit and scope of theinvention as defined in and limited solely by the appended claims.

lclaim:

l. A rotary valve for metered delivery of particulate material into apneumatic conveyor system comprising a generally cylindrical casinghaving a pressure relief port in the upper portion of the casing and amaterial outlet port in the lower portion of the casing for connectionto a pneumatic conveyor system, a rotor rotatably mounted in said casingfor rotation in a predetermined direction relative to said pressurerelief and outlet ports and having a plurality of radial vanes definingtherebetween a succession of compartments for receiving an conveyingparticulate material, means defining a material inlet port in one sideof the cylindrical casing intermediate said outlet and pressure reliefports and disposed in advance of the pressure relief port with respectto the direction of rotation of the rotor so that material entering thecasing through said inlet port is deposited in successive rotorcompartments prior to passage thereof past the pressure relief port, thesaid inlet port being spaced from said pressure relief port andconstructed and arranged to provide an angle of repose of the materialoperable to only partially fill each successive compartment of therotor, the outer edges of the radial vanes being in sealing engagementwith the inner wall of the cylindrical casing intermediate said pressurerelief and outlet ports and intermediate said outlet and inlet ports,and means of the casing defining a pressure relief recess within thecasing radially outward of the rotor vanes and extending between theinlet and pressure relief ports in communication therewith.

2. A rotary valve as clarmed in claim 1 wherern the axial width of saidrotor compartments is greater than the width of the material inlet portin said casing. v

3. A rotary valve as claimed in claim 1 wherein said pressure reliefport includes means preventing the passage of material particles intothe atmosphere.

4. A rotary valve as claimed in claim 3 wherein said latter meanscomprise a dust separator, and a conduit connecting said relief portwith said separator.

1. A rotary valve for metered delivery of particulate material into apneumatic conveyor system comprising a generally cylindrical casinghaving a pressure relief port in the upper portion of the casing and amaterial outlet port in the lower portion of the casing for connectionto a pneumatic conveyor system, a rotor rotatably mounted in said casingfor rotation in a predetermined direction relative to said pressurerelief and outlet ports and having a plurality of radial vanes definingtherebetween a succession of compartments for receiving an conveyingparticulate material, means defining a material inlet port in one sideof the cylindrical casing intermediate said outlet and pressure reliefports and disposed in advance of the pressure relief port with respectto the direction of rotation of the rotor so that material entering thecasing through said inlet port is deposited in successive rotorcompartments prior to passage thereof past the pressure relief port, thesaid inlet port being spaced from said pressure relief port andconstructed and arranged to provide an angle of repose of the materialoperable to only partially fill each successive compartment of therotor, the outer edges of the radial vanes being in sealing engagementwith the inner wall of the cylindrical casing intermediate said pressurerelief and outlet ports and intermediate said outlet and inlet ports,and means of the casing defining a pressure relief recess within thecasing radially outward of the rotor vanes and extending between theinlet and pressure relief ports in communication therewith.
 2. A rotaryvalve as claimed in claim 1 wherein the axial width of said rotorcompartments is greater than the width of the material inlet port insaid casing.
 3. A rotary valve as claimed in claim 1 wherein saidpressure relief port includes means preventing the passage of materialparticles into the atmosphere.
 4. A rotary valve as claimed in claim 3wherein said latter means comprise a dust separator, and a conduitconnecting said relief port with said separator.